(a) Field of the Invention
The present invention relates to an elastic crawler, and in particular, to an elastic crawler which is formed with an elastic material while taking a shape of an endless track, and used as the wheel of the work vehicle under bad working conditions, for example, on the steep and rough road.
(b) Description of the Related Art
Generally, iron belts or tracks that pass over a number of wheels have been commonly used as wheels for work vehicles designed for use under bad working conditions, such as steep and rough road conditions. Such vehicles are produced by, for example, Caterpillar, Inc. (Peoria, Ill.). However, as such iron belts are tracks are heavy, result on poor fuel efficiency, and produce loud noises, elastic crawlers have been recently introduced instead of the iron belts and tracks.
The elastic crawler 1A is, for instance, used as a wheel for work vehicles designed for use under bad working conditions, such as steep and rough road conditions. The elastic crawler 1A is shaped with an endless track (a ring), but for convenience, only a part of the elastic crawler 1A is amplified and illustrated.
Raised lugs are formed at the ground contact side of the crawler body, and concave earth removal portions are disposed between the lug neighbors. The lugs are divided into left and right to the center of the crawler body in the width direction thereof, and overlapped with left and right wings of the cores, respectively. Japanese Patent Laid-open Publication No. 2002-29461 discloses such an elastic crawler.
With the elastic crawler, the one-sided lugs have ground contact surfaces overlapped with the projections of the neighboring wings in the longitudinal track direction, and the opposite-sided lugs have ground contact surfaces overlapped with the projections of the corresponding wings.
The lengths of the ground contact surfaces of the left and the right lugs are different from each other, and those lengths with the respective left lugs as well as with the respective right lugs are also different from each other. The left and the right lugs differentiated in the ground contact length are arranged in a zigzag pattern.
With the elastic crawler disclosed at the above publication, the left and right lugs with ground contact surfaces differentiated in the ground contact length are arranged with a zigzag pattern, and overlapped with the projections of the wings, thereby enhancing the flexibility at a section for wrapping the crawler around the driving wheel, inhibiting the release of the crawler from the sprocket, and reducing the vibration.
However, in such an elastic crawler where the ground contact lengths of the ground contact surfaces of the left and right lugs are different from each other, the lug with a relatively short ground contact length is liable to be deteriorated in rigidity.
Furthermore, when the elastic crawler is circularly operated, the external forces applied to the left and the right lugs are differentiated, and this causes stress to the elastic crawler. In this case, cracks are liable to be made at the stress-concentrated area, resulting in deteriorated reliability and durability of the elastic crawler.
In addition, as the lugs having ground contact surfaces with different ground contact lengths are divided left and right from the center of the crawler body in the width direction thereof, and arranged in a zigzag pattern, any one of the pair of core neighbors is necessarily overlapped or straddled with the lug. For this reason, although slightly improved, it is not possible to obtain sufficient flexibility, and to completely remove the crawler release factor.